Spark plug



Sept. 19, 1933. C. F. WAHL 1,927,621 1 SPARK FLUG Filed May 28, 1932 C7zczrZasf7 Wahl,

Patented Sept) 19, 1933 I IT P STTE'S, 7

- '7 Claims (Cl. 123169) An object cf the invenbion is 130 =provide a, spark plug of novel, msxpensive and;advantageous .construction in which the flow of current from the cent ral electrode 1:0 the:shellj of theplug will bg. interrupted by a plurali ty of spark gaps for intensifying the spark and. ensur ing the ignition of be fuel gases; another object-ofthe invention is '00 provide a nove1 and advantageous means for securing the electrodes Withinthe porcela'in core of the plug; and. a furthler objectof=the invention is to provide a novel ctmstruction;and arrangement of parts for the preventionof the fouling of the electrodes,

With the foregoing an d related obje cts in View the invention resides in the elements and, in the novel .constrnction combination andarrangement thereof hereinafcer described -2u'1d. claimed,

In the accompanying drawing illustrat ing ohe invention,

Figure 1 is a vertical secti on, enlgxrged-of a spa rk plug embodying the invention. Figure 2 is a bottom view thereof. 1

Figure 3 is a transverse section.through the iri sulating cqre, online 38 of Fig. 1.

Figure 4 is a transverse section througlg the in-v sulating core, 011 1ir 1e44 of Fig. 1.

with the electrodes removed therefrom. Referring t0 the drawing, 2 designatesthe metallic she1l or pasing of the plug and 5 the insulating core -therein 1 Thelower portion of the shell 2 isexteriorly threaded, at 6, to permit it to be screwed i nto the usual threaded opening or bore in the wa1 1 0f the manner, and the central portion of the she1l has a hexagonal flange 7 formedthereon to limit the movemen t of the she1l whenjitis screwed into saidopening or boxe.

'I'he lower end of the Shell 2 -is open fo r communication with the combustion chamberof an engine, and the upper ehd 0f j:he shell has a hollow head 8 formed the1:eon haNing a, hexagonal eXterior surfape to receive a Wrenchior turning the p1ug.k v

' Tne core 5 may the head 8, and the top cf the portion 9 is below an i1n1surned flange 11 formed. on 1 ;he upper end Figure 5 is a bottom view of the insulating c o re 1 f '1 1" 'h' th' re, combustion chamber of an engin6, in the usual' v 9 0 the p ug 1S ocated m 1S be formed of Dofdelin in. any other suitable insulafiing mate arial and it cQmcf the head 8. A packi'ng ring 12 is interposed'bctween th e.shoulder 10 and the' bottom of the. expanddportion 9, and6. packing rihg 13 ifs interp 0 sed between theiflange 1*1 and the t0p 01 the" porti'on 9. The packing rings 12 and 13 rnay be forniedof copper or qthe'r suitable mate rial whichwill. form a tight joint and ewoid. vbreaking 'th'e por'celain f 01' other materialforming theco1e} 5. 1

Befdre the shel1 2, core 5 arid=ringsl2 ancl= 1 are assembled, the flange 11 stands upfrom ehe top df the head 8 and its interior diameter' isequa1 the exterior diumeter of 1;he expanded portion 9 of the core 5, a.nd,after the portion9 z a11d rings 12 and 13 have been placed within the head 8, the metal forming th9 upsta11ding fiange 11 is distortedflnd fprced inwa rdlythe posi-'. tior1sh'own. in Fig'. 1 tdfirmlyclampthe portio'n 9 and rings 12 and 13betweenthe shoulderl0 and. flange 11 andthus firmly lock the core 5 in pflace within the shel1 2. v j 'Ihe core.5 has'anupper part.14:which exends Some distance above the he'ad 8 of the shel1 2;

and it has ailower part 15 which eXtends from 22 is th readed for the reception of a suitable nut 25 for c0nnecting a lead wire to the electrode.

Before the electrode 19 is placed within the bore 17, a suitable cen'1ent is intr'oduced to the Same to cement the electrode therein.

One side of the shell 2 is provided with an electrode 26 which extends downwardly from the bottom thereof. One end of the el 'ectrode 26 is firmly secured Within a"bore in the shell 2,

and the other or free ex'1d.portioh 2'7- thereof is bent or turned inwaidly towarcl the axis of the plug.

The lower end portion extends below the bottom of the head 16 andis bent, as shown in Figs. 1 and 2 to provide a free end portion 28 whieh is dil'G-Ct6d0lltlflldlY to ward-the inwardly turneol portion 27 of the eleotrode 26 inalinement therewith, or'subs antiai'iy' so, laut spaced therefrorn.

'Ihe side 01 the head 16 of the co2ke 5 opposite,

to the electrode 26 is" out away or flattoned, at 29, and the heaci 16 -has"a transverse bo1e 30 .therein which extends f1'01n the fiatt'end side th ebreof seine distahce into but not entirelythrough'the head and whichorosses the longitudinal bore 17 therein in spaced relation thereto; and thehead 16 has a kerf 31 therein which extends from the 'openend of the bore 30 to the lower or outer'end of the head 16. The space between the opboSing"side w'allsof the-kerf 31. is equa1, 01 substantially equal, to the diameter-of the bore'30.

' The bore 30 is threaded 'for thefceception of 352 the threaded end portion '32 of an intermediate eler'ztrode 33 WhiCh haS an angular behd34 ther in and which eXtends downwardly or outwardly' froml the bend 34 thro11gh and byohd the kerf 31 and has its f1ee end locatezdbetween-but 'spaced. from the end portions' 27 a'nd28 of the electrodes19 a'nd 26, respectively, to provide two spark ga&ps 34 ancl 35. v

within thebore 30; As an;aclditional means to secure the electrode 33 within the bore.3 0 a'nd kerf 31, a suitablepenient is placed therein bef ore .the partsof theelectrdde are introduoedthereto.

Theprovisioriiof the head 16on the part 15 of the eure 5 and thga locationof the head 16, beyondthe end of the shell 2Qp rovidesample materiell in the.core 5 within which to secure the intermediate eleCtiode 33 andat the -same tim o -i t{permits the desired ample -space between the part' 15of the coreand the inner Wall of the surrounding shell2, for the Dl'evention ofthe accumulation of Carbon around the Glect1ods.

The flattened side 29 of the head 16 alsdassists in'pwventing the accumulation of ca1bon in the region ofthe electrodes. 1 y 'Ihe bottom or inner ehdof theshell 2 is Beveld or incline'd away from the head from the regioh of the"electrode 26 to th'e'opposite side of the shell 2, anol this beVeled o-r inclin ed end'bindfits relatibn tothe'fflatt'ened sicle 29 of the had 16 provides the desire d open space between the head 16andthe adjce'nt end 01" the hell Whil6bl0- viding a suitablri looated support for the electrode 26-.

sipated therefrorn; so that it Wil1 remain quite of the main electiode ;19-

through the bod'y' ahd head thereof, said head 'The head 16 being'considerably larger in di' ameter than the neck o1 part 15 of the core 5 which supports it is 1ess likely to have the heat proVided by the burning gases 01 the engine diS hot at all times, during the runhing of the engine, and thus bu1n any lubricating, 011 which may find its vvay to the heaol.

Iclaimas my irivention:

' 1..A' spark plug.r.comprising a metallic shell, andan insulating eure secured thefein and havirig a longitudinal bore and a threaded, transverse bore crossing the longitudinal bore in spaced relation th reto and having a kerf extending from one end of the transversebore to the encljof the core a main electrocle Within the longitudinal bo1e ancl projecting from one end of the core; an felectrode connected to and projectirig from the shell, and an intermediate electrode having one end. portion thereof thr.eaded andscrevved into said transverse; boreand.hav-

ing the remaining portion-thereof bent intosaid ke'rf andextended the'refrom to a position' between and spaced fiom the firstn'amed oloctrodes} the wallsof said kerf pr venting th-threaded portion of the intermediate Electrodo fromturn- 2. A spark plug oomprising a'rnetallio Shell, an insulating core secured =thefeinfand'having aparts1irrouncledb3r 'and spa"ced fro"m the Wall of the Shell and projecting beyond=the en'd theretqf and havirlg an integral expand'ed fr'e' end'-porti0n forming a headbeyond'the "end of the Shell, said corohavin' a longitudinal-m (extending l1aving a transverse bore thorein 'cro'ssing the longitudinalbore in spacied re1atin therato and a kerf oxtendixigfrm one end of the transverd boxe totheouter end of the heada main eleC-' trode within thelongitudinal'bore and projecting from said head, an-electrode conn otedtdnd projectingyffrom the shell, and an intermediate electrode h'aving an angular bend threin"a'n'd having one end. 1oortion the'reof securfed Witliin thetransverse bore and the'other endp'ortion the1eof e'xtending thi'0gh and beyon'd said kor'f to afpositi0ubet'weeh and spaQced from the 'first riamed electrodes. 1 V 3. A spark plug coinprising a metallic shellan insulating core sebured therein anal having 'a part sur1founded by and spaced from the W tf the shell and pr0jecting blayond the end. thereof and having an expanded free end portion fofming a head beyond the end of the Shell, said core having a longitudinal bore extending through the body2tnd head tbreof Said head having a threaded, tranve'rse bore therein crossing the longitudinal bore in spaced relation theret0 and a kerf extendirig fron'n one end of the, transve1:se bore to the outer end of the hea'd, a mainele'ctrode Within the longitudinal bore and'projeicting from sam head, anti an int'ermediat9 electrode haviiigfone endportionthereof thr'es1ded and screwed irito saifd transverse bore' and= haVin'g the remaining porti0n thereof bent into sa'iol k'erf ELI1C1 Extenciing therefroih 130 a position betvveen and spaced from the first named electrodes, the

Walls of Said kerf pre'venting the threadedporti0n0f the intefmediate ele'ctrode from turnii1g.

4.'Aspark plug cozngirising a metallit: Shell, an insulatihg core secu red therein andhavirig a part surrounded by' an'd spwd f1*omthe Wall 0f the shelland projectingbe5mn'd the end therecif and hai'ring an integral expanded. free e'n'd por-' tion for'ming a h'ead beyond the end of the sh'ell,

a inain electrode witl1in the longitudinal bore and projecting from one end 0f the core, an 'eltactrode connected to and projecting from the shell, and an intermediate electrode having a band therein and having one end portionthereof secured within said head and. the other end portion thereof 9xtending from said head to a position betweien and spaced from the first named electrodes;

5. A spark plug insulating core comprisingan elongated body having an integral expanded portion fdrming a head-on one end of the body and having a longitudinal bore extending thiough the body and the head thereof, for thelrecejotion of an electrode, said head having a threade d trans-- verse bore ther6in crossing the longitudinal bore laterally thereof and having a. kerf extending from one end of the transverse bore so the unter end cf said he ad said transverse bore and ker f being constructed to receive another electrode.

6. A spark plug comprising a metallic shell,--

an insulating core secured therein and having a bore extending longitudinally therethrough and having an expanded end portion, the outer end screwed into the thread of the bore and provided 'with'a fre end portion smalle'r' in-die'x'meter'than the threalded portion thergof, s aid' st'em having an axial bore therein into which one end pqrti0n of said wire extends, and said freeend portiqn being indented againstsaicl Wire.

1 1 3 portionof which is threaded, and a plur'ality' Qf eliactrodes one of Which is connected so the shell and one of which is lokzated within said bore and" comprises a head and a wire extending therefrom,

fsaid head having a'stexn" ext endirig therefromf and provicled with a. thread adjacnt tlu'efe'to- "'7. A spark plu 'g electrode com;irising a 'he ad 1 and a wire extending ther'efromfsaid heac l h:a1v ing a stem ex t6nding therefrom andprovided with a thread'adjacerit the1feto' and halVing a;free

end portion"snialleir in .diametcer t han the threaded 'pdrtion tl 1ereof; said stni havirig' an;

aXial bqr'etherein into Whih one end portion of indented against said-wire andthereby retaining said Wire (extends, and said free end po'rtion being it 'Within said bore. 6 

